The Supreme Commander of Sweden's Armed Forces ordered a rifle battalion of 150 troops currently training on Gotland to remain as a permanent force from 7am today, at least six months earlier than planned.
"External factors in the world have deteriorated over time and so I have made a decision about a permanent presence and that we put the battle group here earlier," Supreme Commander Micael Bydén told public broadcaster SVT News.
He reassured the Swedish public that the decision was nor related to any immediate security threat.
"This is a matter of looking realistically at the world around us, the Armed Forces will now take its responsibility and demonstrate it here with the increased military capability to take responsibility for the country's sovereignty," he said.
Defence Minister Peter Hultqvist also stressed there was no threat of immediate attack, but said Russia's actions had prompted the decision.
"Russian military exercises are increasing steadily in intensity and magnitude," Hultqvist told the newspaper Dagens Nyheter.
"Our assessment is that this situation will last. That is why we're making this decision now," he said.
The Swedish government decided in March 2015 to begin reestablishing a permanent military presence on Gotland within three years. The current force on Gotland will be replaced by other troops at a later date until a permanent unit is established.
The Gotland garrison was previously closed in 2005, ending a continuous Swedish military presence on the island for nearly 200 years.
The Swedish defence budget has increased to SEK 10.2 billion for the period 2016 - 2020.